Report ITU-R S.2363-0
(06/2015)
Interference effect of transmissions from earth stations on board vessels operating in fixed-satellite service networks on terrestrial co-frequency stations
S Series
Fixed satellite service
Foreword
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Series / Title
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Note: This ITU-R Report was approved in English by the Study Group under the procedure detailed in ResolutionITU-R 1.
Electronic Publication
Geneva, 2015
ITU 2015
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Rep. ITU-R S.2363-01
REPORT ITU-R S.2363-0
Interference effect of transmissions from earth stations
on board vessels operating in fixed-satellite service networks
on terrestrial co-frequency stations
(2015)
TABLE OF CONTENTS
Page
1Introduction and background......
2Study 1: Study based on increasing the number of passes of ships in the C and
Ku bands......
2.1Resulting distances......
2.2Protection distance calculations in the 6 GHz and 14 GHz bands using Recommendation ITU-R P.620-6
2.3Protection distance calculations in the 6 GHz band using the Recommendation ITU-R P.452-14
3Study 2: Establishing different protection distances for different maximum e.i.r.p. density levels, which yields shorter protection distances for e.i.r.p. density levels lower than those currently allowed by Resolution 902 (WRC-03)
3.1Initial data......
3.2Protection distances based on short-term protection described in Recommendation ITU-RSF.1650-1 in the band 5 925-6 425 MHz
3.3Protection distances based on short-term protection described in Recommendation ITU-RSF.1650-1 in the band 14-14.5 GHz
3.5Computation of required long-term ESV separation distances for e.i.r.p density levels towards horizon lower that in Annex 2 of Resolution 902 (WRC-03) in the band 14-14.5 GHz
3.6Conclusions......
4Study 3: Establishment of different protection distances for different maximum e.i.r.p. density levels accounting for thestatistical information on maritime traffic and the probability of frequency overlapping
4.1Introduction......
4.2Initial data......
4.3Results for C and Ku bands......
5Summary of studies......
6Summary of studies......
Page
7Concerns of some administrations......
Annex 1 – Path loss calculations...... 30
Annex 2 – Port call statistics...... 31
Annex 3 – Considerations about scenario to be used in the studies...... 37
1Introduction and background
This Report provides the results of studies conducted in response to WRC-15 agenda item 1.8, which calls for a review of the provisions relating to earth stations on board vessels (ESVs) in accordance with Resolution 909 (WRC-12). Inparticular, this agenda item considers the need to review and possibly revise limitations and restrictions contained in Resolution 902 (WRC-03) in light of the current ESV technologies being deployed (e.g. use of spread spectrum modulation), while ensuring the continued protection of other services to which the frequency bands 59256425MHz and 1414.5GHz are allocated.
Consideration of ESVs in the ITU started in 1997 when WRC-97 placed ESVs on the WRC-2000 agenda (agenda item 1.8) in its Resolution 721 (WRC-97).
At WRC-03 diverging views were expressed on the appropriateness of allowing an earth station on board a vessel, which is a maritime mobile earth station, to operate in the fixed-satellite service, with different classes of stations. The Conference decided to authorize earth stations on board vessels to operate in the fixed-satellite service, adopted Resolution 902 (WRC-03), and introduced footnotes RRNos.5.457A, 5.457B, 5.506A and 5.506B.
In particular, Resolution 902 (WRC-03) limits the use of ESVs to distances of at least 125 km “from the low-water mark as officially recognized by the coastal State” for Kuband (14-14.5 GHz)and 300km for Cband (59256425MHz)for operation “without the prior agreement of any administration”.
Since that time, the use of these earth stations on ships has increased but no studies updating the ESV deployment scenario considered in 2003 are available.
However, it should be noted that, for the 14GHz band, Recommendation ITU-R SF.1650-1 uses the number of ferry arrivals of the Dover port in 1999. The number is approximately 24000 and the Recommendation derives the number of vessel passes per day multiplying it by the probability of the frequency overlap. This means the Recommendation assumes that all the ferries are equipped with ESV terminals operating in the 14GHz band.
During the 2007-2012 ITU-R study cycle, an input document called attention to the assumptions used in Recommendations ITU-R S.1587-1 and ITU-R SF.1650-1 to develop Resolution 902 (WRC-03) considering that they are no longer representative of all current ESV technologies. For example, some of the typical ESVs in the frequency band 59256425 MHz may operate today with e.i.r.p. density levels that are more than 20dB lower than those used in Resolution902 (WRC-03).As a consequence, ESV operations at lower power could coordinate more easily with the terrestrial administration if they operate inside the 300km and 125km in C and Ku bands, respectively, or even be allowed to operate at smaller distances without the need to coordinate.
It should be noted that the 5 925-6 425 MHz and 14-14.5 GHz frequency bands are extensively used by the fixed service (FS) in many countries, including terrestrial stations that are near to coastlines and that point toward the sea providing basic infrastructure telecommunications of these countries including broadband communications to remote rural communities and communications to offshore oil platforms.These terrestrial services in many cases provide the backbone of infrastructure in developing countries.
The operation of ESVs as authorized by WRC-03in Resolution 902 (WRC-03), was the result of extensive discussions and compromises made at WRC-03. Some administrations were of the view that it might not be possible to retain those compromises if the criteria and parameters currently in force were to be changed. Therefore, careful studies were required in particular using the course of action and methodologies used in studies before WRC-03.
This Report contains the results of calculations of distances beyond which the agreement of the terrestrial administration is not required, for different values of maximum e.i.r.p. density of the ESV stations, as apossible way to implement the necessary protection of terrestrial co-frequency operations while introducing flexibility in the regulatory framework. The above mentioned values of e.i.r.p. density would be part of the ESV license issued by the licensing administrations.
It is noted that Recommendation ITU-R S.1587-2 shows 6 GHz ESV transmitting power densities at the input of the ESV antenna as low as –11.3 dB(W/MHz), 24.3 dB lower than the value of 13dB(W/MHz) used in the derivation of the Resolution 902 (WRC-03) protection distances. Likewise, for the 14 GHz band, Recommendation ITURS.1587-2 shows ESV transmitting power densities as low as –13.5 dB(W/MHz), 22 dB lower than the value of 8.5dB(W/MHz) used in the derivation of the Resolution 902 (WRC-03) protection distances. These ESV systems are the main incentive for carrying out the studies reflected in this Report.
Although it is not expected that all ESV systems will operate with the same low power levels in the future due to the diversity of service requirements, one of the approaches to adapt the regulatory environment to the reality of ESV systems operating with different levels of uplink power density is to allow smaller protection distances for systems with low power density levels, which will effectively make the ESVs appear indistinguishable to the fixed service receivers. Consequently, the spread and distribution of the e.i.r.p. densities will not be a factor to be considered.
In addition, if smaller ESV antennas are to be allowed, the number of vessels equipped with such terminals is likely to increase, which will in turn lead to a greater number of likely ESV passes per day as considered in Recommendation ITU-R SF.1650-1. This would require the base assumptions/simulations of Recommendation ITU-R SF.1650-1 to also be revisited. However, thereare no 14 GHz ESV systems described in Recommendation ITU-R S.1587-2 with antennadiameters smaller than 60 cm, the minimum diameter taken into account in Resolution902(WRC03). As to 6 GHz ESV systems, the minimum antenna diameter found in Recommendation ITU-R S.1587-2, 1.2 m, is smaller than the minimum diameter considered in Resolution 902 (WRC-03). This fact needs to be taken into consideration and is addressed in detail later in thisReport.
Since not all vessels will have the new ESVs with e.i.r.p. density levels that are more than 20 dB lower than those used in Recommendation ITU-R SF.1650-1, the maximum e.i.r.p. density levels towards the horizon, ascurrently contained in Annex 2 to Resolution 902 (WRC-03), must still be considered as the worst-case for the calculation of protection distances.
2Study 1: Study based on increasing the number of passes of ships in the C and Ku bands
One study presented the results of calculations of the off-shore distances from the baseline for protection of the fixed services in the bands 5925-6425MHz and 14-14.5 GHz, for a new range of co-frequency vessel passes (see Table1below), with 36° discrimination angle and technical ESV andfixed service receiver(FSR) parameters, as mentioned in Recommendation ITU-R SF.1650-1, using the propagation model described in Recommendation ITU-R P.620-6, as the following:
Table 1
Number of vessel passes across the beam of the fixed service receiver (FSR)
Frequency band / Number of vessels6 GHz band / 1 vessel every third day; 1, 3,4 and 6 vessels every day
14 GHz band / 3,6 and 8 vessels every day
The values of the parameters used for the fixed stations have been tabulated in the following Table2 and the other parameters are those which were used in the Recommendation ITU-R SF.1650-1.
Table 2
FSR parameters
Frequency band / Bandwidth (MHz) / TFSR (K) /6 GHz band / 11.2 / 750 / 3
14 GHz band / 14 / 820 / 3
Using the parameter values described above and based on the methodology specified in Recommendation ITU-R SF.1650-1, the off-shore distance can be calculated as shown in the following Tables 3, 4, 5 and 6 for both 6 GHz and 14 GHz bands.
These Tables show the effect of number of vessels equipped with ESV on the protection distance for CandKu bands. Calculations have been performed for three different antenna discrimination angles: 10°, 20° and 36°, maximum ESV transmit power at input to antenna is set to16.7 dBW for 6GHz and 12.2 dBW for 14GHzand latitudes are set to 20° and 45°.
To investigate the effect of the distance of the station from shore on the protection distance, results are presented for two cases: the FSR located on the coast (0 km inland) and the FSR located some distance inland (25 km inland for the 6 GHz band and 15 km for the 14 GHz band). As it is seen, by increasing the number of vessels the protection distance also increases.
2.1Resulting distances
As mentioned above, the ESV parameters agreed upon in Recommendation ITU-R SF.1650-1 have been considered for calculation of the minimum distance. However, it is reasonable to assume that the number of ESVs has increased, and the importance of this parameter was indicated in the above mentioned Recommendation.
Furthermore, it is believed that the definition of the adequate distance to protect the FS should be based upon calculations relative to 36° discrimination.
Therefore, taking into account the new assumptions of the maximum numbers of vessels 4 and 6 for C band and also the maximum numbers of vessels 8 for Ku band with 36° discrimination angle, it is proposed to retain the following administrative protection distances as the recommended off-shore distances for both the C and Ku bands which would not cause unacceptable interference to the FS services.
–345 km in the C band;
–125 km in the Ku band.
It means that, with increasing the numbers of the passing vessels, taking into account the operations of ESVs, 300km for C band could not be reduced but should be increased to the proposed off-shore value, as mentioned above, but the off-shore distance of 125 km for the Ku band could be retained as it is in current Resolution 902 (WRC-03).
2.2Protection distance calculations in the 6 GHz and 14 GHz bands using Recommendation ITU-R P.620-6
Calculation results in the 6 GHz band
TABLE 3
Protection distance in the 6GHz band using Recommendation ITU-RP.620-6,
latitude=20, BFSR=11.2MHz, Pt=16.7 dBW
Antenna discrimination angle (degrees) / 10 / 20 / 36 / 10 / 20 / 36
Lb(dB) / 170.7 / 163.7 / 156.7 / 170.7 / 163.7 / 156.7
1 vessel every third day / Distance (km) / 452 / 379 / 307 / 377 / 333 / 282
P (%) / 0.0439 / 0.0523 / 0.0646 / 0.0526 / 0.0596 / 0.0703
1 vessel every day / Distance (km) / 472 / 397 / 322 / 397 / 352 / 299
P (%) / 0.0139 / 0.0166 / 0.0204 / 0.0166 / 0.0187 / 0.0220
3 vessels every day / Distance (km) / 490 / 413 / 336 / 414 / 369 / 313
P (%) / 0.0045 / 0.0053 / 0.0065 / 0.0053 / 0.0059 / 0.0070
4 vessels every day / Distance (km) / 494 / 417 / 340 / 418 / 373 / 317
P (%) / 0.0033 / 0.0039 / 0.0048 / 0.0039 / 0.0044 / 0.0052
6 vessels every day / Distance (km) / 501 / 423 / 345 / 424 / 378 / 322
P (%) / 0.0022 / 423 / 0.0032 / 0.0026 / 0.0029 / 0.0034
TABLE 4
Protection distance in the 6GHz band using Recommendation ITU-RP.620-6,
latitude=45, BFSR=11.2MHz, Pt=16.7 dBW
Antenna discrimination angle (degrees) / 10 / 20 / 36 / 10 / 20 / 36
Lb(dB) / 170.7 / 163.7 / 156.7 / 170.7 / 163.7 / 156.7
1 vessel every third day / Distance (km) / 427 / 356 / 286 / 344 / 299 / 247
P (%) / 0.0465 / 0.0557 / 0.0694 / 0.0577 / 0.0664 / 0.0803
1 vessel every day / Distance (km) / 451 / 378 / 305 / 368 / 323 / 270
P (%) / 0.0146 / 0.0174 / 0.0216 / 0.0179 / 0.0204 / 0.0244
3 vessels every day / Distance (km) / 472 / 397 / 322 / 389 / 343 / 289
P (%) / 0.0046 / 0.0055 / 0.0068 / 0.0056 / 0.0064 / 0.0076
4 vessels every day / Distance (km) / 477 / 402 / 326 / 394 / 348 / 293
P (%) / 0.0034 / 0.0041 / 0.0050 / 0.0042 / 0.0047 / 0.0056
6 vessels every day / Distance (km) / 484 / 408 / 332 / 400 / 354 / 300
P (%) / 0.0023 / 0.0027 / 0.0033 / 0.0027 / 0.0031 / 0.0037
Calculation results in the 14 GHz band
TABLE 5
Protection distance in the 14GHz band using Recommendation ITURP.620-6,
latitude=20, BFSR=14 MHz and Pt=12.2 dBW
Antenna discrimination angle (degrees) / 10 / 20 / 36 / 10 / 20 / 36
Lb (dB) / 162.8 / 155.8 / 148.8 / 162.8 / 165 / 148.8
3 vessels every day / Distance (km) / 215 / 165 / 116 / 213 / 160 / 115
P (%) / 0.0080 / 0.0104 / 0.0147 / 0.0080 / 0.0107 / 0.0149
6 vessels every day / Distance (km) / 219 / 169 / 119 / 218 / 164 / 118
P (%) / 0.0039 / 0.0051 / 0.0072 / 0.0039 / 0.0052 / 0.0072
8 vessels every day / Distance (km) / 221 / 171 / 121 / 219 / 165 / 120
P (%) / 0.0029 / 0.0038 / 0.0053 / 0.0029 / 0.0039 / 0.0053
TABLE 6
Protection distance in the 14GHz band using Recommendation ITURP.620-6,
latitude=45, BFSR=14 MHz and Pt=12.2 dBW
Antenna discrimination angle (degrees) / 10 / 20 / 36 / 10 / 20 / 36
Lb (dB) / 162.8 / 155.8 / 148.8 / 162.8 / 165 / 148.8
3 vessels every day / Distance (km) / 208 / 159 / 110 / 203 / 155 / 108
P (%) / 0.0082 / 0.0108 / 0.0156 / 0.0084 / 0.0111 / 0.0159
6 vessels every day / Distance (km) / 213 / 163 / 114 / 208 / 160 / 112
P (%) / 0.0040 / 0.0053 / 0.0075 / 0.0041 / 0.0054 / 0.0076
8 vessels every day / Distance (km) / 214 / 165 / 116 / 210 / 162 / 113
P (%) / 0.0030 / 0.0039 / 0.0055 / 0.0031 / 0.0040 / 0.0057
In the meantime, for the calculations in the 6GHz band, the FSR antenna height is taken as 120m above mean sea level. Although this is representative of most cases, in some countries fixed links are located on mountains with an altitude of about 1000m which should be considered in the ITUR studies, as appropriate.
2.3Protection distance calculations in the 6 GHz band using the Recommendation ITU-R P.452-14
The calculations have been made for the fixed stations with the altitudes of120m and 1035m above the sea level. In the first case, the fixed station with the altitude of 120 m above the sea level and distance of zero from the shore have been considered.In the second case, the fixed station with the altitude of 1035m above the sea level and distance of 25km from the shore have been considered.
Using the parameter values described above and based on the methodology specified in Recommendation ITU-R SF.1650-1 and using the propagation model described in Recommendation ITU-R P.452-14, the results show that almost the same conclusion is reached for C band (~ 345 km) using the propagation model described in Recommendation ITURP.6206. Therefore, it is confirmed that the off-shore distance of 300 km for C band in uplink directions should be increased. To this effect, it is necessary to examine and remedy the assumptions again in Recommendation ITUR SF.1650-1.
3Study 2: Establishing different protection distances for different maximum e.i.r.p. density levels, which yields shorter protection distances for e.i.r.p. density levels lower than those currently allowed by Resolution 902 (WRC-03)
This study follows the same methodology described in Recommendation ITU-R SF.1650-1 and the propagation model described in Recommendation ITU-R P.452-14, and also takes into account different values of uplink transmitted power density for ESVs employing state of the art technologies and technical characteristics and, for the 6 GHz band, a doubling in the number of passes of ships when compared with the number assumed by WRC-03. The latter assumption results from the proposed reduction of the 6 GHz ESV minimum antenna diameter from 2.4 to 1.2m, with the consequent potential increase in aggregate interference into terrestrial services.
This study also considers, for the 14 GHz band, different values of uplink ESV transmitted power density and the deployment scenario of ESVs implicitly assumed by WRC-03 when establishing the protection environment for the FS, including the number of passing vessels used during the studies carried out before WRC-03.
The assumption that the number of passing vessels used during the studies carried out before WRC03 is still valid today is based on updated maritime traffic statistics in certain regions, shown in Annexes2 and 3 of this Report.
3.1Initial data
For the original assessment of the protection distances found in Recommendation ITU-R SF.16501, the technical characteristics of ESVs contained in RecommendationITU-R S.1587-1 were used.However, Recommendation ITU-R S.1587-2 presents technical characteristics of two new types of ESVs which were absent in Recommendation ITUR S.1587-1, namely System 5 and System4 in the C and Ku frequency bands, respectively.
Tables 7 and 8compare, for the C and Ku frequency bands, the ESV parameters used for the derivation of the protection distances found in Recommendation ITU-R SF.1650-1 and the ESV parameters of the new systems added in Recommendation ITU-R S.1587-2.
TABLE7
ESVs parameters in the frequency band 5 925-6 425 MHz
(frequency of operation – 6000 MHz, antenna height above sea level – 40 m)
System 5 / Comment
Elevation angle to satellite, degrees / 10 / Lower elevation angles may be used provided that the e.i.r.p. towards the horizon is consistent with the 10 elevation angle operational limitation
Emission type (modulation) / QPSK/CDMA
Horizon gain angle, degrees / 0 / According to Recommendation
ITURSM.1448 in the worst case
Data rate, kbit/s / 1544 / 38.4/76.8/128
Maximum occupied bandwidth, MHz / 2.346 / 9.14/18.29/
30.48
Transmit power, dBW / –1.2/3.3/4.8
Maximum transmit power at input to antenna, dBW / 16.7 / –1.7/2.8/4.3
(calculated) / Considering feeder loss
Transmit e.i.r.p. the density at input to antenna, dB(W/1MHz) / 13.0
(calculated) / –11.3/–9.8/
–10.5
Minimum antenna diameter, m / 2.4 / 1.2
Antenna gain in direction of the fixed service receiver, dBi / 4 to10 / According to Recommendation
ITURSM.1448
Antenna main beam gain, dBi / 41.7 / 35.7
Transmit e.i.r.p. density, dB(W/1MHz) / 54.8
(calculated) / 24.4/25.9/25.2
TABLE8